The present application is directed to brake-by-wire braking systems and, more particularly, to full brake-by-wire braking systems with a hydraulic fail-safe.
Modern vehicles, including electric vehicles, hybrid vehicles and traditional petroleum-powered vehicles, may include numerous electrical and computerized systems, such as brake-by-wire braking systems. Brake-by-wire braking systems typically replace the traditional mechanical and hydraulic fluid connection between the brake pedal and the braking units (e.g., disk or drum brakes) with an electrical connection (i.e., brake-by-wire). The electrical connection typically communicates user input signals from the brake pedal to a control unit and the control unit in turn controls the operation of the brake units to apply or release a braking force.
A disadvantage associated with brake-by-wire braking systems is the risk that a single failure loss of electrical power will disable the brake system, leaving the vehicle operator with no means for stopping and/or controlling the vehicle. Attempts have been made to reduce the risks associated with an electrical failure by providing redundant or multiple independent electrical systems complete with separate battery reserves to serve as back-up systems in the event of an electrical system failure. However, such redundant electrical systems substantially increase manufacturing and system costs and typically increase the overall complexity of the electrical system.
Accordingly, there is a need for a brake-by-wire braking system having a hydraulic fail-safe feature that can reduce manufacturing and system costs and electrical system complexity, as well as provide a simple, robust and proven source of braking energy in the event of electrical system malfunction.